Public awareness of environmental issues has steadily increased over the past few decades. As a result, the general public now demands a quality environment with clean air in which to live, work and entertain. Various types of air filtering systems are used in residential and commercial buildings to improve the quality of the air. One commonly used type of air filter system is the "bag" or "pocket" filter designed to significantly increase filtering surface areas in an air flow passage. Another type designed for the same purpose is the V-bank filter which doubles the filtering surface area, compared to a planar filter in the same air flow passage.
A known pocket filter uses multiple filter bags arranged in housing of a suitable shape. The manufacture of such bag filters is expensive because the disposable filter bags have to be interconnected using a sewing or gluing process.
Pocket air filters are assembled in several ways. For example, they may be constructed of folded wire grids which are secured between end walls to receive filter material consisting of a glass wool, cotton wool or textile cloth supported by resilient removable frames. An example of a pocket filter structures is taught in U.S. Pat. No. 3,691,736, entitled POCKET FILTER FOR AIR AND GAS PURIFICATION which issued to Neumann on Sep. 19, 1972.
Passive bag, pocket and V-bank filters are, however, not particularly efficient for removing small particulates suspended in air. This is especially true in environments contaminated with heavy smoke, such as casinos and bars, or industrial facilities used for welding, etc. In such environments, it has been demonstrated that high performance electrostatic air filters are superior to passive bag or V-bank filters for removing impurities from the air.
Electrostatic air filters generally include a disposable filter cartridge of a charged media type and a filter cartridge holder which is provided with a high voltage power supply for charging the filter. Electrostatic air filters of the charged media type are well known and taught in U.S. Pat. No. 4,886,526 entitled ELECTRONIC AIR FILTRATION SYSTEM, which issued to Joannou on Dec. 12, 1989. Joannou teaches a disposable filter cartridge which is supported by a support frame constructed to facilitate servicing the filter without having to handle individual filter pads. The disposable filter cartridge consists of an inner screen of conductive material which is sandwiched between a pair of dielectric, fibrous pads. This inner screen is connected via an electrode to one side of a high voltage power supply to electrostatically charge the filter cartridge. An outer surface of the fibrous filter pads are in turn covered by a pair of conductive screens which are connected to the other side of the power supply. These outer screens may be a part of the disposable filter cartridge or a part of the support frame, but both embodiments function in the same way.
Electrostatic V-bank air filters are constructed from a pair of electrostatic air filters supported by V-shaped side panels which are installed in an air bonding system. The pair of filters share the air cleaning load of air drawn through an air intake end at a wide end of the V-shaped side panels. Because of their air cleaning efficiency and ease of maintenance, there is a rapidly increasing demand for electrostatic V-bank air filters. They have become particularly popular in public places with significant air quality problems, such as casinos and bars where cigarette smoke is a particular concern. They are also gaining acceptance in animal husbandry where they are used for odour and disease control in cattle and hog barns, and poultry houses. They are also expected to rapidly gain acceptance in office and commercial buildings where they contribute to air quality.
The Applicant manufactures and sells electrostatic V-bank air filters in which each V-bank unit includes two substantially triangular side panels with rectangular top and bottom electrostatic filter units transversely secured to side edges of the respective side panels. The filter units are constructed of extruded metal and plastic frame elements, such as disclosed in the Applicant's U.S. Pat. No. 5,059,218, entitled CONSTRUCTION FOR SUPPORTING A FLEXIBLE SHEET which issued to William E. Pick on Oct. 22, 1991. While these V-bank filters perform well, sub-assembly of each filter unit is required before assembly of the V-bank unit. This is a time consuming and labour intensive process.
Consequently, there is a need for a structure for electrostatic V-bank air filters which facilitates manufacture and assembly of V-bank air filters to reduce manufacturing costs and decrease assembly time.